1. Field of the Invention
The present invention relates to monolithic electronic components, and more particularly, to the structure of terminal electrodes disposed on the external surfaces of a component body having a monolithic structure so as to be electrically connected to internal electrodes.
2. Description of the Related Art
In general, the noise of an IC power supply line is removed by connecting a bypass capacitor between the power supply line and the ground. When a printed circuit board that is almost entirely covered with a power supply conductor pattern or a grounding conductor pattern is used in order to achieve high-density mounting, resonance often occurs between the power supply and the ground. Since the occurrence of resonance leads to the occurrence of radiation noise, resonance needs to be suppressed.
However, if a monolithic ceramic capacitor, which typically has an equivalent series resistance (ESR) as small as several milli-ohms and a self-resonance frequency of about 1 MHz to about 100 MHz, is used as a bypass capacitor to control such resonance, the impedance in this frequency band becomes small. Consequently, the resonance described above and occurring within a band of about 1 MHz to about 100 MHz cannot be suppressed.
Generally, it is known that resonance can be suppressed by connecting a resistor in series with a monolithic ceramic capacitor. To enable resonance suppression in such a manner, Japanese Unexamined Utility Model Registration Application Publication No. 62-184728 and Japanese Unexamined Patent Application Publication No. 11-283866, for example, disclose a monolithic ceramic capacitor having a structure where the resistor is connected in series by incorporating the resistor into the terminal electrodes of the monolithic ceramic capacitor itself, not by connecting the resistor as a discrete component to the monolithic ceramic capacitor. In particular, Japanese Unexamined Patent Application Publication No. 11-283866 discloses the formation of a resistor film as a foundation for terminal electrodes by using a resistive paste containing conductive particles and curable resin, and the formation of an electroplating film thereon.
However, when performing electroplating on the resistor film as disclosed in Japanese Unexamined Patent Application Publication No. 11-283866, if the volume resistivity of the resistor film is high, electric current does not easily flow during electroplating, which makes it difficult to perform the electroplating.
Furthermore, even if a plating film can be formed on the resistor film, it is difficult to form the plating film with a uniform thickness. As a result, thinner regions of the plating film easily allow entry of moisture and moisture resistance may be degraded. In addition, since the bonding strength between the resistor film and the plating film is relatively weak when the thickness of the plating film is not uniform, separation of the plating film from the resistor film often occurs when heat is applied during a mounting step or the like, thus leading to changes in resistance.
While the above description relates to monolithic ceramic capacitors, the same problems maybe encountered with other monolithic electronic components having terminal electrodes with resistor films.